OF-58: Log username of failed SASL logins

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@11231 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/openfire/sasl/SaslServerPlainImpl.java

@@ -138,10 +138,10 @@ public class SaslServerPlainImpl implements SaslServer {
             throw new SaslException("UTF8 not available on platform", e);
         } catch (UnsupportedCallbackException e) {
             aborted = true;
-            throw new SaslException("PLAIN authentication failed", e);
+            throw new SaslException("PLAIN authentication failed for: "+username, e);
         } catch (IOException e) {
             aborted = true;
-            throw new SaslException("PLAIN authentication failed", e);
+            throw new SaslException("PLAIN authentication failed for: "+username, e);
         }
         return null;
     }